1. Field of the Invention
This invention relates to a lifting cushion apparatus for lifting, supporting, or moving heavy loads and wherein the apparatus comprises a plurality of chambers at least one of which has a wedge-like shape when inflated.
2. Description of the Prior Art
Lifting cushions are known to those of ordinary skill in the art and have been used for the raising or supporting of loads which have a low specific surface strength relative to their weight. Such loads would include, but not be limited to the following examples: airplanes, busses, tank cars, trucks, subway cars, and the like. Prior art lifting cushions are generally cylindrical or cubic in form. The sidewalls of such cushions are frequently constructed of polyamide filament weave which has been made air-tight through the use of a coating of synthetic rubber or gum. The cushions are usually provided with an upper surface having a head plate thereon and a lower surface which is attached to a bottom plate. The head plate and the bottom plate of prior art lifting cushions typically have a flexible level-like consistency and are constructed to be resistant against deterioration which may be caused by oils or gasoline as well as being resistant to damage from pointed or sharp edged objects. It is also known in the prior art that the head plate and the bottom plate can be constructed of several layers of air-tight weave. A plurality of non-elastic bands may be provided between the head plate and the bottom plate in order to prevent them from bellying out during the inflation process.
The lifting cushions known in the prior art have the disadvantage that in the inflated condition the orientation of the head plate is substantially parallel to that of the base plate. Unfortunately, the head plate of such prior art lifting cushions cannot mold themselves sufficiently to the surfaces to be lifted or supported. For example, such cushions are not readily adapted to support cylindrical or rounded objects such as airplanes in an optimum manner. The prior art has attempted to overcome this disadvantage in some instances by providing the head plate with an additional foam cushion typically having an abrasion resistant covering. Unfortunately, it has been found that foam cushions of that sort have not substantially improved the effectiveness of the apparatus. It is, therefore, a purpose of the present invention to provide a lifting cushion which will give lifting support to surfaces which subtend an angle with respect to the plane on which the object rests.